Feature comparison
| Feature | MailStrike | Instantly |
|---|---|---|
| Automated warmup | ✓ Yes | ✓ Yes |
| Google Workspace integration | ✓ Yes | ✓ Yes |
| Microsoft 365 integration | ✓ Yes | ✓ Yes |
| Volume model | Monthly allocation | Daily ramp-up |
| AI personas (behaviour signalling) | ✓ Fast Scanner, Avg Reader, Thorough Reader, Mobile-First | — |
| Multi-mailbox team simulation | ✓ Distinct persona per mailbox | — |
| Industry personalised sending (AI-powered) | ✓ Yes | — |
| Company description personalised sending (AI-powered) | ✓ Yes | — |
| Rescues from spam (documented) | ✓ Documented | ✓ Documented |
| Marks as important | ✓ Yes | ✓ Yes |
| Dashboard surfaces | Readiness score, 90-day placement chart, live activity feed | Deliverability score, inbox vs. spam metrics |
| Free Email Auth Checker | ✓ SPF / DKIM / DMARC / MX / BIMI | — |
| Free Blacklist Checker | ✓ 21 blacklists | — |
| Free SPF / DKIM / DMARC generators | ✓ All three | — |
| Free Email Template Analyser | ✓ Yes | — |
| Continuous warming alongside campaigns | ✓ Yes | ✓ Yes |
Cells marked “—” aren't documented in publicly available product material at time of writing.
Where they actually diverge
The cadence. Instantly uses a daily ramp where warming volume increases gradually each day on a fixed schedule. MailStrike runs on monthly allocation, which gives the engine room to vary daily volume the way a real domain does and to lean into the days the network engages best.
Who the mailboxes pretend to be. MailStrike runs four personas (Fast Scanner, Avg Reader, Thorough Reader, Mobile-First), one assigned per mailbox. Different reply timings, different dwell, different active hours. The receiving algorithm sees a team, not a single behaviour repeated.
What the mailboxes write about. Instantly generates warming content. MailStrike generates warming content using your industry and company description as prompt context. The second matters when receivers are looking for content fingerprints: a fintech sender sending fintech-flavoured warming is harder to flag than a fintech sender sending generic SaaS warmup.
What you get alongside. Instantly bundles warming into a full outreach platform. MailStrike publishes a free diagnostic stack (Auth Checker, Blacklist Checker, record generators, template analyser) that anyone can use, with the warming engine as the core product.